LXR busybox/coreutils/tac.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * tac implementation for busybox
   4 *
   5 * Copyright (C) 2003  Yang Xiaopeng  <yxp at hanwang.com.cn>
   6 * Copyright (C) 2007  Natanael Copa  <natanael.copa@gmail.com>
   7 * Copyright (C) 2007  Tito Ragusa    <farmatito@tiscali.it>
   8 *
   9 * Licensed under GPLv2, see file LICENSE in this source tree.
  10 *
  11 */
  12
  13/* tac - concatenate and print files in reverse */
  14
  15/* Based on Yang Xiaopeng's (yxp at hanwang.com.cn) patch
  16 * http://www.uclibc.org/lists/busybox/2003-July/008813.html
  17 */
  18
  19//usage:#define tac_trivial_usage
  20//usage:        "[FILE]..."
  21//usage:#define tac_full_usage "\n\n"
  22//usage:        "Concatenate FILEs and print them in reverse"
  23
  24#include "libbb.h"
  25
  26/* This is a NOEXEC applet. Be very careful! */
  27
  28struct lstring {
  29        int size;
  30        char buf[1];
  31};
  32
  33int tac_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  34int tac_main(int argc UNUSED_PARAM, char **argv)
  35{
  36        char **name;
  37        FILE *f;
  38        struct lstring *line = NULL;
  39        llist_t *list = NULL;
  40        int retval = EXIT_SUCCESS;
  41
  42#if ENABLE_DESKTOP
  43/* tac from coreutils 6.9 supports:
  44       -b, --before
  45              attach the separator before instead of after
  46       -r, --regex
  47              interpret the separator as a regular expression
  48       -s, --separator=STRING
  49              use STRING as the separator instead of newline
  50We support none, but at least we will complain or handle "--":
  51*/
  52        getopt32(argv, "");
  53        argv += optind;
  54#else
  55        argv++;
  56#endif
  57        if (!*argv)
  58                *--argv = (char *)"-";
  59        /* We will read from last file to first */
  60        name = argv;
  61        while (*name)
  62                name++;
  63
  64        do {
  65                int ch, i;
  66
  67                name--;
  68                f = fopen_or_warn_stdin(*name);
  69                if (f == NULL) {
  70                        /* error message is printed by fopen_or_warn_stdin */
  71                        retval = EXIT_FAILURE;
  72                        continue;
  73                }
  74
  75                errno = i = 0;
  76                do {
  77                        ch = fgetc(f);
  78                        if (ch != EOF) {
  79                                if (!(i & 0x7f))
  80                                        /* Grow on every 128th char */
  81                                        line = xrealloc(line, i + 0x7f + sizeof(int) + 1);
  82                                line->buf[i++] = ch;
  83                        }
  84                        if (ch == '\n' || (ch == EOF && i != 0)) {
  85                                line = xrealloc(line, i + sizeof(int));
  86                                line->size = i;
  87                                llist_add_to(&list, line);
  88                                line = NULL;
  89                                i = 0;
  90                        }
  91                } while (ch != EOF);
  92                /* fgetc sets errno to ENOENT on EOF, we don't want
  93                 * to warn on this non-error! */
  94                if (errno && errno != ENOENT) {
  95                        bb_simple_perror_msg(*name);
  96                        retval = EXIT_FAILURE;
  97                }
  98        } while (name != argv);
  99
 100        while (list) {
 101                line = (struct lstring *)list->data;
 102                xwrite(STDOUT_FILENO, line->buf, line->size);
 103                if (ENABLE_FEATURE_CLEAN_UP) {
 104                        free(llist_pop(&list));
 105                } else {
 106                        list = list->link;
 107                }
 108        }
 109
 110        return retval;
 111}
 112